Traction battery controller utilizing voltage rebound of parallel-connected battery cells to detect for a thermal event

Abstract

A method for detecting a thermal event of a battery, such as a traction battery of an electrified vehicle, includes monitoring a voltage of a group of parallel-connected cells of the battery. In response to confirming that the voltage of the group has a voltage rebound, a thermal event of the battery is detected. The detection of the thermal event may further depend on detection of a deviation of another operating parameter, such as temperature or pressure, of the battery.

What is claimed is: 
     
       1. A method comprising:
 confirming that a voltage of a group of parallel-connected cells of a battery has a voltage rebound; and 
 generating an alert indicative of a thermal event of the battery in response to (i) the voltage having the voltage rebound and (ii) either a temperature of the battery being greater than a predetermined temperature or a pressure of the battery being greater than a predetermined pressure. 
 
     
     
       2. A method comprising:
 confirming that a voltage of a group of parallel-connected cells of a battery has a voltage rebound, wherein confirming that the voltage has the voltage rebound includes confirming that the voltage within a selected time range has the voltage rebound; and 
 generating an alert indicative of a thermal event of the battery in response to the voltage having the voltage rebound. 
 
     
     
       3. The method of  claim 2  wherein:
 confirming that the voltage within the selected time range has the voltage rebound includes confirming that a peak-to-peak value of a derivative of the voltage within the selected time range is greater than a predetermined threshold. 
 
     
     
       4. The method of  claim 3  wherein:
 confirming that the voltage within the selected time range has the voltage rebound includes confirming that the derivative of the voltage within the selected time range has a zero-crossing. 
 
     
     
       5. The method of  claim 2  wherein:
 confirming that the voltage within the selected time range has the voltage rebound further includes confirming that a derivative of the voltage within the selected time range has a zero-crossing. 
 
     
     
       6. The method of  claim 1  wherein:
 the battery is a traction battery of an electrified vehicle. 
 
     
     
       7. A system comprising:
 a sensor configured to monitor a voltage of a group of parallel-connected cells of a battery; and 
 a controller configured to generate an alert indicative of a thermal event of the battery in response to detecting that the voltage has a voltage rebound, wherein the controller is configured to detect that the voltage has the voltage rebound in response to detecting that a peak-to-peak value of a derivative of the voltage within a selected time range is greater than a predetermined threshold. 
 
     
     
       8. The system of  claim 7  further comprising:
 a second sensor configured to monitor an operating parameter of the battery; and 
 wherein the controller is further configured to generate the alert in response to (i) detecting that the voltage has the voltage rebound and (ii) detecting that the operating parameter of the battery has a deviation. 
 
     
     
       9. The system of  claim 8  wherein:
 the operating parameter of the battery is a temperature of the battery. 
 
     
     
       10. The system of  claim 8  wherein:
 the operating parameter of the battery is a pressure of the battery. 
 
     
     
       11. The system of  claim 7  wherein:
 the controller is further configured to detect that the voltage has the voltage rebound in response to further detecting that a derivative of the voltage within the selected time range has a zero-crossing. 
 
     
     
       12. The system of  claim 7  wherein:
 the battery is a traction battery of an electrified vehicle.